class Stack(object):
    def __init__(self):
        self.stack = []

    def push(self, value):
        """
        :param value: 入栈
        :return:
        """
        self.stack.append(str(value))
        return True

    def pop(self):
        """
        :return: 返回最后入栈的值
        """
        if self.stack:
            item = self.stack.pop()
            return item
        else:
            return False

    def top(self):
        """
        :return: 返回第一个值
        """
        if self.stack:
            return self.stack[-1]
        else:
            return False

    def length(self):
        """
        :return: 返回栈长度
        """
        return len(self.stack)

    def view(self):
        """
        :return: 返回栈逗号表达式
        """
        return ",".join(self.stack)
